In general, such a power transmission apparatus for a vehicle such as an automotive vehicle and the like is provided with a parking lock mechanism which is adapted to make it impossible for rotational elements and parts to be rotated by engaging a parking pawl with a parking gear secured to a rotation shaft forming part of the power transmission apparatus when the vehicle is manually shifted from its traveling range to its parking range for the stoppage of the vehicle.
As one of the conventional parking lock mechanisms of this kind is known a parking lock mechanism as shown in FIG. 21 (see for example Patent Document 1). The conventional parking lock mechanism shown in FIG. 21 comprises a manual shaft not shown) to be rotated in response to the operation of a shift lever to be operated by a driver, a detent lever 111, integrally connected with the manual shaft, and a parking rod 112 having one end potion connected with the detent lever 111, so that the parking rod 112 is axially moved in response to the swinging motion of the detent lever 111.
The parking rod 112 is disposed to be received in a cylindrical rod guide 113 with its forward end portion projecting toward a sleeve 114 adjacent to the parking rod 112. The forward end portion of the parking rod 112 has a parking cam 115 securely mounted thereon, and the sleeve 114 is formed with an inclined surface 114a allowing the parking cam 115 to slide thereon.
Above the sleeve 114 is provided a parking pawl 116, and above the parking pawl 116 is provided a parking gear not shown and rotated together with the rotation shaft.
The parking pawl 116 is formed with a tooth to be engageable with the parking gear, so that when the parking cam 115 slides on the inclined surface 114a formed on the sleeve 114 in response to the axial movement of the parking rod 112, the parking pawl 116 is pushed upwardly by the parking cam 115 in a direction perpendicular to the axial direction of the parking rod 112.
The parking pawl 116 thus pushed upwardly by the parking cam 115 causes the tooth formed on the parking pawl 116 to be engaged with the parking gear, so that the rotation shaft rotated together with the parking gear can be locked, thereby stopping the vehicle.